"I was just saying I don't feel safe," Professor Charles K. Smith told the San Antonio Express-News.
Campus carry was signed into law in 2015 and officially implemented into Texas community colleges on August 1 - the same day Smith wore the bulletproof vest and helmet to class, WGHP reports.
The law, that went into effect at four-year institutions last year, allows people with a license to carry a concealed handgun on college premises.
"It definitely makes me feel uneasy that there are more firearms on campus than there really should be," Smith told the newspaper. "(Dressing this way) was just a statement on how I felt."
Stay on top of breaking news stories with the ABC11 News App
One of Smith's students posted a photo of the professor on his Facebook and it has generated more than 500 comments.
One user commented, "Can't blame him. If I were still teaching at STC I'd probably consider this, especially around grading time."
However, several other comments called the professor a "liberal hack," a "reactionary, liberal moron" and suggested he should be fired for being "anti-Constitutional."
Smith told the Express-News he ran his plan by police and school administration beforehand.
"Some of them were OK and some of them weren't, but it's freedom of speech," he told the newspaper.